If the decision were ever taken, what would be the best method of defending our planet against killer comets or asteroids?
So what if we decided to protect ourselves from Comets and Asteroids, what would we have to do? What would be the best, and most cost efficient way we could go about saving our world if ever the need came?
We should say first that there will be an outcry against such a step, or rather the financial expenditure associated with a comet defense at a time when finances world wide are not that great. However, before condemning the idea, read on a little and you may realize that it is not all expensive to set up a last ditch defense-just in case.
On first thought
The first method ever proposed was of course the most obvious : to use a thermonuclear device mounted on a rocket ship and aim it towards the intruder. But just as soon as the idea was proposed all sorts of objections would be raised. The most prevalent was that the very idea of having a nuclear device in space really scared many people and so the idea was then sent away in favor of a new search.
Billiard Space Ball
The next idea to come up was simply to send a high speed rocket towards the asteroid, or comet so that it could be deflected away from Earth. The problem with that idea however, is that we would really need to get this rocket up to very high speed in a hurry, and that is really not feasible since the best way to actually do that is to have it sling shot past the planets themselves. The time it would take to get it to the planet Mars, or Jupiter would likely not be enough. We are not very likely to have more than a few months warning in the case of a comet, and if it is large, then we could not hope to deflect it sufficiently enough since we could not send something massive enough into space to do the job.
Land on it and push
The next idea to come along was to send a probe to actually land on the comet or asteroid, and then fire some kind of consistent thrust so as to nudge it away from Earth. This could work only if we have a few years warning, which might be the case with the few asteroids we have been able to monitor, but it would be completely worthless in the case of a newcomer from deep space since we would not have enough time to land the craft etc. In the case of a very large comet, the idea would not work at all since we would not have all that much thrust to work with. Getting huge, heavy amounts of rocket fuel into space is really not very practical, or even possible just now. At least not in a single launch.
Let attraction save us
Yet another idea that came along was quite creative and intelligent. The possibility of having a craft cruise by a large asteroid and allowing the craft’s own gravity to nudge the asteroid out of the way seemed like a good idea after all. If we were to park the craft a few feet away from the asteroid and allow the ships gravitational pull to act on the asteroid after a few months we could conceivably draw it off course. But once again reality stepped in and it became quite obvious that we would again not likely have that kind of time in most cases, and also if the asteroid or comet were very large the negligent gravitational field generated by the small craft would not be enough to pull the intruder out of the way in time. Also the idea of waiting for gravity to save the world seemed a bit too much for the nerves of the population of Earth should such a scenario come to actuality. Too many people might lose their patience and their mind waiting for the gravitational force of a small spacecraft to nudge a killer comet out of the way in time.
There are a few ideas concerning the use of very powerful Earth based lasers and the like to destroy, or deflect the comet or asteroid but once again there are difficulties. This time the technology stands in the way since we do not as yet have lasers with quite enough energy to do so. Eventually this idea might actually turn out to be feasible, at least for small bodies near the Earth, but when it comes to large comets or asteroids, there would not be enough energy to deflect or destroy such a body using an Earth based laser, or group of lasers. Event aiming such a laser would be very difficult to say the least. We should remember that not only is the Earth itself rotating, but also is traveling through space at tremendous speeds along with the rest of the solar system. There are also all kinds of motions, and orbital oscillations to deal with, such the seasonal tilt, as well as the precession of the Earth, which though slow would still make it difficult to keep a laser focused on a distant object also traveling through space at enormous speeds, while rotating over a particular axis. About the only way to actually do that would be to get a broadcast radio source to land on the asteroid or comet and digitally signal back the exact coordinates at which to fire. But that would be risking too much and would involve too much time and uncertainty in the end. Thus any laser defense is most likely to be in the far future when these things get more practical, and would more likely be used for objects that are small and about to hit the Earth if ever this tool is to be developed and used for this purpose.
Old idea was best after all
In the end the only good idea was really the first idea. Thermonuclear devices mounted on a spacecraft. The reality is that such a device could be sent to deal with Asteroids or Comets rather quickly, and deal with even very large bodies that might head towards Earth. A one hundred mega-ton Hydrogen Bomb detonated next to a large comet would in all probability be more than enough to both disintegrate it, and scatter it in some other direction than towards our planet. Even if the asteroid or comet were only a hundred million miles away(which is a relatively small distance astronomically speaking) such a device, or series of devices could easily and efficiently obliterate such a threat in a few days.
The enormous blast and heat would be enough to disintegrate even a large metallic asteroid of the hardest and heaviest kind, and probably even deal with a much larger Ice comet, possibly melting and scattering most of it away from Earth making it harmless. Even if a few particles were to come towards Earth after such a blast, they would probably pose no real threat since they would almost certainly be small enough to disintegrate in the atmosphere, and there would be very minimal leftover radiation to really worry about as most of it would have scattered into space. For the most part, depending on just how near the intruding body might be, there would not very likely be any debris to worry about at all since most all of it would be long scattered far away from Earth.
It could of course require the detonation of a number of such devices in succession, but if the life of the planet were at risk, we would have ample cause to consider such a serious, and dangerous action. In the end, when fighting for the life of an entire planet, almost any action might be justified when one thinks carefully about it.
Politics and Money
The real obstacle would be political, and financial. The nuclear nations, the United States, Russia, China, England, France, India, and Pakistan might not be very happy knowing that such a device was heading into space. For this reason they would all have to be involved with not only the staging and testing of such a device, but with the costs as well. This would not be a project for only one nation. Israel and North Korea are said to have the bomb as well, thus these two would probably also have to be convinced that this really is a peaceful mission for everyone’s good. All the other non-nuclear nations would be no less concerned as well. So they too would have to be inducted into some part of the process, and possibly some part of the cost. This would be a global project if ever it were decided to protect our planet in the unlikely event that such a catastrophic threat should ever materialize during any particular lifetime.
There would be cost to be sure. But for the most part we have the technology to launch readily available. To mount a large bomb on top of a rocket is really not much different that most of the satellite payloads we are used to sending up. There would be ample fail safes built it that make it very unlikely that anything catastrophic should happen in the event of an accident. Certainly the bomb would only be armed once in space and far from Earth. Again not a difficult feat. In the end the only new technology needed might be to increase precision of positioning next to an intruder. But this again is already being developed as even this moment there is a European space craft actually positioning itself next to a comet. True some better improvements might be needed in positioning directly, quickly and efficiently, but this is probably not going to be too much of a challenge. In the end all need be done is to intercept the intruder at the right angle and detonate; something much less difficult than the present rendezvous being undertaken by the Europeans. So the technological curve is really not fantastic.
The real issue is finding such an intruder. That could involve a bit more cost believe it or not, than actually destroying an intruder. The art of finding such objects is not an easy art. Especially when it comes to comets. As we have said before comets are difficult to find. They are dark for one thing, they are very distant, and really dont show up till they start to fire up as they approach the Sun. That is a serious problem. Moreover, they tend to come in at oblique angles, so astronomers often tend to miss them, even if they are very large. Still with the cooperation of many nations, a simple system of detection could easily be developed. If the technology exists to destroy these objects then all we have to do is decide how far away we need to absolutely detect such an object in order to be able to destroy it in time. When this perimeter is determined, we can then focus on patrolling only that perimeter perhaps. We certainly do not need to know much else if and when we have the immediate ability to destroy such an object, for example we really do not necessarily need to know its long period orbit or where it will be a thousand years from now since no matter when it makes its appearance, we will be able to deal with it in time. Thus discover becomes less important, and simple detection is needed if a strong defensive barrier is brought into development.
For the most part all of this is possible, and would not have astronomical costs. The costs would be somewhat greater than launching a satellite but probably not much more. It would also allow for much international cooperation with technology and space exploration and defense, and maybe give all these nations a solid real reason to live together instead of always trying to compromise each other.
Yet the greatest value may well be the symbolic meaning behind the effort. Ever since the creation of Nuclear weapons it has been obvious that their only use is to destroy human life and to leave behind a vast amount of poison and destruction. Indeed, should these weapons ever be used in earnest for the purpose of war, they would probably result in the extinction of humanity and the possible extinction of all life on Earth save but the most primitive, leaving behind a vast radioactive wasteland that few living things could survive. But if we were to use these weapons for the protection of Earth, we would have reversed forever the final judgment on this technology. It could go from being a weapon of mass destruction, to being the savior of all life on Earth. We would use these weapons not to kill ourselves, and every other living thing with us, but to save ourselves from extinction and possibly save the Earth itself from possible total destruction! An irony if ever there were one. The idea of all nations working together to insure that life on Earth would continue even in the face of one the most destructive forces in the solar system is if nothing else a noble thought, a spiritual endeavor in itself. It might well mean having snatched life right from the jaws of death, both figuratively, and practically in the event that a large comet or asteroid, or groups of comets or asteroids were suddenly seen heading for our planet.
Practical minds will oppose, but they may risking the world in doing so
It’s a high notion, far, and wide, and probably hard for some to grasp or accept because the practical mind is more adept to dealing with what is here and now, and not what may be some time in the distant future. But there would be some benefits here and now too. Indeed, the space program has itself had the benefit of giving us satellite technology, but not much more in terms of practical implements. With such a system to protect against the possibility of asteroids or comets, it might move to actually give us all a general sense of protection, and a sense of common interest, and common toil, no matter who we are or where we live on Earth. Perhaps through the process of destroying these objects, some other process might evolve, like harnessing their mineral wealth for example. Many asteroids are flying gold mines with tons of ore and minerals of all kinds. There may be trillions of dollars of usable wealth up there. And comets may well have the greatest of all natural resources, water! So harnessing these things is one possible outcome of trying to destroy them when they get too close. If one thing is true it is that often the perceived goal in technology is not the final goal, nor the most valuable. Developing a capability such as needed to defend against a killer intruder from space might lead to much more than just a defensive system. But when all is said and done, it just might save us from the worst catastrophe of all-the end of all life on Earth.
One last thought
Even if the full implementation of such a system is not put into place immediately due to financial considerations, it would not hurt to at least develop a fully functioning blue print, or plan for a last second defense against a killer comet or asteroid. This would cost almost nothing by comparison. It would only involve that governments ask that those qualified begin to draw up serious contingencies with the object of protecting our world should the threat ever arise. In a very short time, a contingency could be created both in theory, and even in practice as present day technology is slightly adjusted for possible use as protection against the worst disaster that could befall our society. A little planning could be all the difference-even if a full blown defense is not yet feasible.
See Shiva Hypothesis
also Comet Siding Spring